According to the survey carried out by NASA's Wide-field Infrared Survey Explorer with its subsequent NEOWISE mission, Holt measures 5.03 kilometers in diameter and its surface has an albedo of 0.28,[5] while the Collaborative Asteroid Lightcurve Linkassumes a standard albedo for stony asteroids of 0.20 and derives a diameter of 6.44 kilometer with an absolute magnitude of 13.32.[4][6][7]

After his retirement, Holt was a principal participant in the Palomar Asteroid and Comet Survey (PACS) from 1983 to 1993.[8] Holt has discovered and co-discovered six comets and 683 minor planets between 1989 and 1993,[9] including 4581 Asclepius,[10] a potentially hazardous asteroid that has made the closest approach to Earth of all numbered asteroids.[2] The official naming citation was published by the Minor Planet Center on 30 January 1991 (M.P.C. 17656).[11]